A top Lashkar--Taiyba terrorist was in Karachi for the last three months to help organise the worst-ever terrorist attack in Mumbai, the New York Times reported on Friday, citing a Pakistani official in contact with the terror outfit.

Zaki-ur-Rehman Lakhvi, the Lashkar-e-Taiba commander, was in Karachi for the last three months to help organise the terrorist attack in Mumbai, the report said.

The Mumbai attackers also kept in contact with their handlers in Pakistan through cell phones as they rounded up guests at the two hotels, it said, quoting officials.

The attackers left a trail of evidence in a satellite phone they left behind on the fishing trawler they hijacked near Karachi at the start of their 500-mile journey to Mumbai, the report said.

The phone contained the telephone numbers of Yusuf Muzammil, a LeT terrorist considered to be the mastermind of the Mumbai attack, Rehman and a number of other Lashkar terrorists, the Times said, citing a report on the Mumbai siege prepared by M J Gohel and Sajjan M Gohel, two security analysts who direct the Asia-Pacific Foundation in London [Images].

The numbers dialed on the phone found on the trawler, used to call Muzammil, matched the numbers on the cell phones recovered from the Taj and Oberoi hotels, the report said.

Based on evidence found on the trawler, it was possible that five other men were involved in the plot and were still at large, the paper said.

In one of the hotels, a terrorist asked several Indian guests what caste they belonged to and what state they came from, the Times quoted an official, who interviewed the guests, as saying.

Once the attacker found out these details, he then called someone believed to be Muzammil, who was in Lahore [Images], according to phone records recovered by investigators.

The surviving guests said the terrorist told the person on the other end of the phone the guests' details and asked whether they should be killed or not.

At one point, a guest said one of the calls seemed to be a conference call with two people on the other end.

Once the calls were finished, the paper said, the terrorist moved the small group of guests, who did not know what their fate would be, into a room. When the attackers became distracted by tear gas fired by the police, the hostages managed to escape.

In another instance, the Times said, the terrorist forced a Singaporean hostage at the Oberoi hotel, Lo Hwei Yen, to call her husband in Singapore. She told him that the hostages were demanding that Singaporean officials tell India not to try a rescue operation. The next day, Lo was killed, the foundation's report said.

Investigators found that after the terrorist killed her, they used the phone she had called her husband with, it said.

"The worrying scenario is that Muzammil may have ordered her execution along with two other hostages that were found murdered in the same room," the report was quoted as saying.